It's fascinating reading others' opinions of what makes the "best" wheel. It really is a personal thing, depending on the kind of yarn you are making, your spinning style and your individual body! You really have to try them out yourself. I don't think that either scotch tension or dd is inherently better. Same with single or double treadle. I learned to spin in 1973, my first wheel was an Ashford Trad kit wheel, which was the only widely available manufactured wheel at the time. It was a clunker, and since I learned to spin with my right hand forward, it was awkward, but I don't think those things are bad for a beginner.
In the early '80's I bought an early Lendrum and spun miles of yarn on that one. Now I have a Lendrum double-treadle and love it, but it did take me some time to get used to using both feet! With my back problems, it's much better for me to sit facing the wheel with a balanced pelvis. The Lendrum is a great travelling wheel, unless you are flying, I like my Bosworth box for that. The Lendrum has lots of optional equipment, and it can be made into a very fast wheel. My main wheel is (like Nancy's) a Watson Marie, double treadle with the flyer on the right. I figured that after 35 years in the craft I deserved a custom made wheel! I can't say enough good things about this fabulous, beautiful wheel, or it's maker. It is very BIG, though. It's my first dd wheel, and it's wonderful for fine yarn especially if you intend to ply it. I can spin on Marie for hours, it's very light treadling. I still use the Lendrum for soft spun singles, rug yarn and plying. I have to disagree with the idea that the brake stops the wheel cold when you are not treadling...the Lendrum doesn't free-wheel like my Marie does, but then Marie has a heavy 30-inch wheel. For some yarn, it is useful to be able to adjust the spinning speed and the pull-on speed separately, not possible with dd. Lynn C Seattle